Most recipes for baking (as opposed to cooking/frying/roasting) will require a solid fat such as butter or lard and as such need that solid fat for the final product such as a sponge cake. That does not mean an oil can not be used, and in fact I have come across 2 very good recipes (one a cake and the other for cookies) that use oil rather than butter or a solid fat, but they do have very different textures to what people are used to and expect.
I also think a lot of it is regional. In the Mediterranean for example, keeping something like butter not only solid but fresh, in the summer months would have been quite difficult. Here in the UK, in the winter it is not uncommon for oil to solidify in its bottle and have to be warmed up in order to get it out of the bottle (at least in my kitchen it is not uncommon)!